Public Reason

Public reason requires that the moral or political rules that regulate
our common life be, in some sense, justifiable or acceptable to all
those persons over whom the rules purport to have authority. It is an
idea with roots in the work of Hobbes, Kant, and Rousseau, and has
become increasingly influential in contemporary moral and political
philosophy as a result of its development in the work of John Rawls,
Jürgen Habermas, and Gerald Gaus, among others. Proponents of
public reason often present the idea as an implication of a particular
conception of persons as free and equal. Each of us is free in the
sense of not being naturally subject to any other person’s moral
or political authority, and we are equally situated with respect to
this freedom from the natural authority of others. How, then, can some
moral or political rules be rightly imposed on all of us, particularly
if we assume deep and permanent disagreement amongst persons about
matters of value, morality, religion, and the good life? The answer,
for proponents of public reason, is that such rules can rightly be
imposed on persons when the rules can be justified by appeal to ideas
or arguments that those persons, at some level of idealization,
endorse or accept. But public reason is not only a standard by which
moral or political rules can be assessed: it can also provide
standards for individual behavior. Because we make moral and political
demands of each other, if we are to comply with the ideal of public
reason, we must refrain from advocating or supporting rules that
cannot be justified to those on whom the rules would be imposed. We
should instead, some insist, only support those rules we sincerely
believe can be justified by appeal to suitably shared or public
considerations—for example, widely endorsed political values
such as freedom and equality—and abstain from appealing to
religious arguments, or other controversial views over which
reasonable people are assumed to disagree. In this way, public reason
can be presented as a standard for assessing rules, laws,
institutions, and the behavior of individual citizens and public
officials.

This entry is structured around questions about the nature of public
reason that continue to be the subject of sustained debate in the
literature. Section 1 considers competing positions regarding the
underlying rationale for public reason. Section 2 identifies different
views about the appropriate scope of public reason. Does it apply to
all moral rules, only to political rules, or only to some sub-set of
political rules? Section 3 considers the question of public
reason’s constituency: to whom must our rules be justifiable in
order to be considered legitimate or authoritative? The next question,
in section 4, concerns the content of public reason; in particular, to
what extent is this content determined via a process of philosophical
reflection as opposed to actual moral deliberation? Section 5
considers the structure of public reason, with particular focus on
whether public reason requires some shared perspective or set of
considerations, or whether it can be achieved without any common moral
or political perspective. Section 6 addresses the site of public
reason: where do its norms properly apply and when do they regulate
individual conduct? Section 7 identifies some of the most influential
objections that have been pressed against the idea of public reason,
and Section 8 concludes with a brief survey of a few further
topics.

The idea of public reason appears to inhabit a middle ground between
two more familiar standards of evaluation in moral and political
philosophy. On the one hand, there is consent. Some political
philosophers, for example, argue that political legitimacy requires
the actual or implied consent of the governed (Otsuka 2003,
89–113; Simmons 1999). On the other hand, there is
truth: we can simply ask whether any alleged moral or
political principle is true. Public reason does not aim either at
consent or truth. Public reason instead requires that our moral or
political principles be justifiable to, or reasonably acceptable to,
all those persons to whom the principles are meant to apply. An
account of public reason must find some way of giving the perspective
of individual persons a significant role, without allowing this to
collapse into consent: public reason is not simply a way of
identifying those principles to which people already consent. But
equally, public reason must not define those principles that could be
justified to, or be acceptable to, each person as simply those
principles that are true. In either case, the idea of public reason
would do no independent work.

This apparent middle ground between consent and truth may seem
puzzling in several respects. One puzzle is whether there is, in fact,
a coherent and stable way of explicating the notion of reasonable
acceptability or justification (Raz 1990, 46; Enoch, 2015). But even
if we assume the idea of public reason is coherent, we can plausibly
ask why we ought to accept this idea, that is, what is the basis for
adopting public reason as the relevant standard to evaluate rules and
to govern individual conduct? This section considers five different
answers to this question (these answers can, of course, also be
combined). It is helpful to begin by considering these different
positions regarding the basis of public reason, since how one chooses
to answer this question often has direct implications for the scope,
constituency, content, site, duties, and structure of public
reason.

Each of the positions below is usually combined with an assumption
about pluralism or reasonable disagreement over a wide range of moral,
ethical, and other philosophical matters. That is, virtually all
proponents of public reason assume that there is deep and intractable
disagreement amongst some people, and this disagreement is not simply
the result of irrationality, prejudice, or self-interest, but rather
arises as a result of the normal functioning of human reasoning under
reasonably favorable conditions. This assumption about pluralism or
disagreement is an essential part of the rationale for public reason
since without it, it is difficult to understand why our moral or
political principles ought to be justifiable or acceptable to others,
as opposed to simply true or correct. The most influential conception
of such pluralism or disagreement is Rawls’s account of the
burdens of judgment and the subsequent fact of reasonable
pluralism (Rawls 1996, 36–37, 55–57), though this
account is controversial, and has been subject to extensive criticism
(e.g. Galston 2002, 46–47; Gaus 1996, 131–136; Wenar 1995,
41–48).

Some philosophers present the idea of public reason, or the public use
of reason, as an essential and central part of the nature of rational
discourse about moral norms. Habermas’s influential account of
discourse ethics (Habermas 1990; Habermas 1996) has been presented by
some as grounding a conception of public reason in this way. On this
view, the validity of moral and political norms can only be
established by an intersubjective and idealized practice of
argumentation. Only through an inclusive and noncoercive discursive
process where all participants are equally situated can genuinely
intersubjectively valid norms emerge. Habermas thus proposes a
dialogical principle of universalization, (U), stating that a moral
norm “is valid just in case the foreseeable consequences and
side-effects of its general observance for the interests and
value-orientations of each individual could be
jointly accepted by all concerned without
coercion” (Habermas 1998, 42). For Habermas, this principle
follows from the presuppositions of rational moral discourse. Thus, at
least on one interpretation, to engage in reasoned moral or political
argument with others is to commit oneself to something like the idea
of public reason—to commit oneself to finding norms that could
be jointly accepted by all concerned without coercion. On this
account, public reason is grounded in the nature of reasoned moral
argument: one cannot, without contradiction, avoid the idea of public
reason insofar as one wants to engage in reasoned moral or political
argument with others.

Although Habermas’s account of discourse ethics has been
influential amongst those who favor some version of discursive or
deliberative democracy (Bohman 1996; Chambers 1996; Dryzek 1990;
Dryzek 2000), its capacity to serve as the basis for public reason is
the subject of a number of criticisms. Perhaps most importantly, by
grounding public reason in a broader account of truth, validity, and
rational argument, public reason becomes tied to a specific and
controversial philosophical doctrine. But some proponents of public
reason believe its role is to serve as a mechanism of justification
amongst persons who reasonably disagree about philosophical and other
issues typically embedded in what Rawls calls comprehensive
doctrines (Rawls 1996, 13). If one believes the idea of public
reason should stand apart from any particular comprehensive doctrine
or philosophical theory of truth and rationality, the appeal to the
presuppositions of rational discourse will be a problematic basis for
public reason (see Rawls 1996, 376–381).

Others, most notably Gaus, argue that the idea of public reason
follows from certain basic features of our everyday moral practices
and reactive attitudes, along with certain claims about the nature of
reasons (Gaus 2011). On this view, social morality involves a
particular kind of interpersonal relationship; one where we claim the
standing to make demands of others, and where, under the right
conditions, we acknowledge the standing of others to make demands on
us (Gaus 2011, 184). But for this sort of relationship to exist, we
must believe that when we make moral demands of others, those others
have sufficient reasons to comply with our demands—if they did
not have sufficient reasons to comply, then the reactive attitudes
that form an essential part of the interpersonal relationship of
social morality would cease to make sense (Gaus 2011, 205–232).
If, as Gaus maintains, different people have different reasons
depending on their differing epistemic positions and sets of justified
beliefs, the practice of making moral demands of others must involve
public reason: the moral demands we make on others must be justifiable
to those others by appeal to reasons they have, and not simply by
appeal to the truth as we see it.

Although it differs from discourse ethics in important respects, this
account also promises to ground public reason in a broader account of
the nature of social morality and epistemology. It is thus also
vulnerable to similar worries about whether public reason ought to be
embedded in a comprehensive and controversial philosophical theory of
morality and epistemology.

On one prominent view, with both Kantian and Rousseauvian roots,
freedom requires that we obey only those laws or rules that we could
rationally give to ourselves. To be subject to the will of others, or
to the arbitrary forces of nature, is to be unfree. We thus express
our nature as rational and autonomous beings by acting in accordance
with maxims that we could will to be universal laws, or we express our
political autonomy by acting in accordance with those laws that appeal
only to the common good, and thereby represent the general will of all
citizens. Insofar as one holds this conception of autonomy to be of
fundamental importance, autonomy might thus provide the basis for
public reason. By ensuring that our moral or political principles are
justifiable or reasonably acceptable to all those to whom the
principles apply, public reason appears to ensure that each of us is,
in some important sense, governed only by principles that we can
rationally give to ourselves. Some leading philosophers of public
reason appear to make this connection between public reason and
autonomy. Gaus, for example, appeals to Rousseau’s statement
that the fundamental problem to which the social contract is meant to
be the solution is to find a way of imposing rules to regulate our
common life “in which each, while uniting himself with all, may
still obey himself alone, and remain as free as before” (Gaus
2011, 1. Also see Rawls 1996, 219).

But the extent to which the appeal to autonomy can, on its own,
justify the various features of public reason is uncertain, and many
proponents of public reason do not explicitly present the appeal to
Kantian or Rousseauvian autonomy as the sole, or even primary, basis
for public reason. This may be partly explained by the fact that this
conception of our autonomy, particularly insofar as it is presented as
part of a broader account of our nature as rational beings, is
controversial and the subject of reasonable disagreement (Weithman
2002, 188–191; Quong 2013).

A widely endorsed view regarding the moral basis of public reason
appeals to a particular conception of what it means to treat others
with the respect they are due. On this view, we treat others as mere
means, and not as ends, when we coerce them on the basis of reasons or
arguments that they could not reasonably accept. Charles Larmore, for
example, argues “to respect another person as an end is to
require that coercive or political principles be as justifiable to
that person as they presumably are to us” (Larmore 1999, 608).
Conversely, “if we try to bring about conformity to a rule of
conduct solely by the threat of force, we shall be treating persons
merely as means, as objects of coercion, and not also as ends,
engaging with their distinctive capacity as persons” (Larmore
1999, 607. Also see Larmore 2002 and Nagel 1987). Public reason is
presented as the way of ensuring that our coercion of others is
consistent with respecting others as ends: we do this by ensuring our
coercive actions and institutions can be justified to all those who
are the subjects of coercion. Some argue, more strongly, that public
reason therefore involves a presumption in favor of liberty (Gaus
2011, 341–46).

By grounding public reason in an account of how coercion can be
suitably respectful, this view limits the scope of public reason in
ways that may seem troubling. Not all laws and political institutions
are coercive, and yet some noncoercive political institutions may seem
appropriate topics of public reason. For example, which forms of
marriage, if any, ought to be granted legal recognition, or how the
proceeds of a state-run lottery ought to be spent, might seem
important topics of public reason, but fall outside the scope of
public reason on this basis (Bird 2014; Quong 2013). A related worry
is this: if coercive actions uniquely stand in need of public
justification, then this may make it difficult, or even impossible,
for the state to legitimately pursue many goals that are widely
perceived to be permissible (Lister 2010; Lister 2013).

An alternative, though largely neglected, basis for public reason
appeals to the importance of a particular conception of political
community or civic friendship (Ebels-Duggan 2010; Leland and van
Wietmarschen, 2017; Lister 2013). On this account, the practice of
public reason is a constitutive part of a valuable relationship. This
relationship might be characterized in several ways. The relationship
might have the same structure as other communitarian relationships. In
the same way relationships between co-nationals might be intrinsically
valuable, and constituted by particular social practices (e.g. shared
language and cultural traditions), membership in a pluralistic
political community might be valuable, and constituted, in part, by a
practice of public reasoning amongst citizens with regard to political
rules and institutions. Only when our political community is regulated
by laws that can be justified to each of us, despite our diverse
perspectives, do we stand in the appropriate sort of valuable communal
relationship with our fellow citizens (Lister 2013, ch. 5). A related,
but slightly different view, appeals to a conception of reciprocity
that obtains when people are willing to propose and abide by fair
principles of cooperation acceptable to others, provided those others
are likewise willing (Rawls 1996, 49–50). Rawls suggests that
one role for this criterion of reciprocity ‘as expressed in
public reason…is to specify the nature of the political
relationship in a constitutional democratic regime as one of civic
friendship’ (Rawls 1996, li. Also see Leland and van
Wietmarschen, 2017). Rawls has presented public reason as part of the
idea of democracy itself, especially the relationship in a democratic
society between free and equal citizens (Rawls 1996, 213; Rawls 1999b,
573). On this view, “the idea of public reason specifies at the
deepest level the basic moral and political values that are to
determine a constitutional democratic government’s relationship
to its citizens and their relation to one another. In short, it
concerns how the political relation [of free and equal citizens] is to
be understood” (Rawls 1999b, 574). The value of this
relationship might thus provide at least part of the moral basis for
public reason.

This potential basis for public reason is currently one of the less
well-developed in the literature, and thus important features of the
view require elaboration. For example, does this view presuppose a
particular and controversial conception of the good life? And why
should we believe that the value of civic friendship has enough weight
to ground a very particular conception of the type of reasons that can
be appropriately deployed in political deliberation? A full evaluation
of this alleged basis for public reason would need to consider these
and other issues.

On one common view, public reason is a distinctively political idea:
it paradigmatically applies to the laws and other political
institutions of our society. One way to explain its distinctively
political nature is to ground the idea of public reason in the value
of justice (Quong 2013; Rawls 1996). On this view we begin with an
ideal of society as a fair system of social cooperation between free
and equal citizens. As Rawls says, this ideal “provides a
publicly recognized point of view from which all citizens can examine
before one another whether their political and social institutions are
just. It enables them to do this by citing what are publicly
recognized among them as valid and sufficient reasons singled out by
that conception itself…the aim of justice as fairness, then, is
practical: it presents itself as a conception of justice that may be
shared by citizens as a basis of a reasoned, informed, and willing
political agreement. It expresses their shared and public political
reason” (Rawls 1996, 9). Ensuring that the principles that
regulate our shared political life can be justified to each citizen by
reference to this common point of view—showing these principles
can be the subject of public reason—is how we can know that the
terms that regulate our political institutions are fair, and therefore
just. If our political principles were instead justified by appeal to
some reasonably contested moral, philosophical, or religious doctrine,
the terms of our public life would not be fair. Public reason, on this
view, is the only way to achieve justice given certain assumptions
about the nature of well-ordered liberal democratic societies. This
rationale for public reason has several advantages (Quong 2013).
First, it explains the distinctively political focus of public reason.
Second, justice is widely agreed to be an important value, arguably
“the first virtue of social institutions” (Rawls 1999a,
1), and thus if public reason is grounded in the value of justice,
this would also explain what some take to be an important feature of
public reason, namely, that its conclusions ought to have a certain
deliberative priority for citizens. Finally, the value of justice can
be endorsed by people from diverse religious, moral, and philosophical
backgrounds, and so the value of justice can provide a relatively
uncontentious basis for public reason.

But this view of the basis of public reason also faces important
objections. Some will deny that political principles, even under
conditions of reasonable pluralism or disagreement, need to be
justifiable to each (reasonable) citizen in order to be fair or just.
Others will object that this account does not provide the real
foundation for public reason—it merely shifts the focus to the
value of justice. Unless we can explain the basis for giving justice
such practical importance, we lack an account of the importance of
public reason. Others may object, more strongly, that justice cannot
have deliberative priority or practical importance when restricted to
those principles capable of being the subject of public reason. Some
of these objections are considered in greater detail in section 7.

What is the scope of public reason? To which topics or domains of
moral and political life does the idea of public reason apply? On
Rawls’s influential account, the idea of public reason applies
to what he calls the constitutional essentials and matters of
basic justice within a liberal democratic society, “but not
in general for all the questions for all the questions to be settled
by the legislature within a constitutional framework” (Rawls
2001, 91). Rawls suggests that “citizens and legislators may
properly vote their more comprehensive views when constitutional
essentials and matters of basic justice are not stake; they need not
justify by public reason why they vote as they do” (Rawls 1996,
235). Constitutional essentials, for Rawls, include: the principles
that structure the government and political process (e.g. rules
determining who may vote, and whether a system is parliamentary or
presidential), and the basic rights and liberties of citizens (Rawls
1996, 227). Matters of basic justice involve principles regulating the
distribution of important resources (e.g. income, wealth) not covered
by the list of basic rights and liberties (Rawls 1996,
228–229).

This proposal about the scope of public reason has been subject to two
main challenges. First, some doubt that there is a coherent way of
drawing the distinction between constitutional essentials and matters
of basic justice on the one hand, and matters of ordinary political
legislation on the other (Greenawalt 1994, 685–86). Almost
everything the government chooses to do (or not to do) would seem to
have an impact, even if indirect, on the basic rights and liberties of
citizens, or else on the distribution of resources in society. Second,
assuming a satisfactory answer to the first question is possible; we
can ask why public reason should be restricted in the way Rawls
proposes? Why not extend public reason to all instances where citizens
exercise political power over one another? Rawls offers no
well-developed answer to this question, though a number of possible
arguments can be found in his work. These arguments appeal either to
the special importance of the basic structure of society, or
to the basic interests of citizens, or to the importance of
public reason being complete, that is, of being capable of
generating at least one determinate answer to important political
questions. But some deny any of these arguments, or some conjunction
of them, can in fact justify restricting the scope of public reason to
constitutional essentials and matters of basic justice (Quong 2011,
273–289).

An alternative view—derived from the account of respect and
coercion discussed in sect. 1.3—expands the scope of public
reason to cover all instances where some person or group exercises
coercive power over another person or group (Larmore 1996, 137;
Larmore 1999, 607–608; Nagel 1991, 159). On this view, the scope
of public reason extends to almost all state action and activity,
since the state’s actions are backed by coercive power, but it
will also extend to include the non-political use of coercion by
private actors. Although this account may seem more clearly defined,
it is also vulnerable to the charge of being both over and under
inclusive. It seems underinclusive, as mentioned in sect. 1.3, because
some state activities are expressive or symbolic, rather than
coercive, but may still seem to stand in need of public justification.
But it may also seem overinclusive because private individuals
sometimes exercise coercive power over one other in contexts (e.g.
private associations or the workplace) where the idea of public reason
may seem inappropriate.

Finally, an even broader account extends the scope of public reason to
the whole of social morality, that is, “the set of social-moral
rules that require or prohibit action, and so ground moral imperatives
that we direct to each other to engage in, or refrain from, certain
lines of conduct” (Gaus 2011, 2). On this view, the idea of
public reason ought to apply whenever we purport to have the standing
to tell others how they ought to behave. Being the most ambitious
conception of the scope of public reason, this view is naturally
vulnerable to worries that it is too expansive, including parts of
morality that are in fact governed by different standards (e.g.
religious standards of conduct). As noted in sect. 1.1, it is also an
account that depends on a particular philosophical conception of
epistemology and moral psychology.

To whom do the relevant rules or principles need to be justified?
Which persons, that is, are to be included in the constituency of
public reason? The most obvious answer is that everyone to whom the
rules are meant to apply must be included in the constituency of
public reason. But this simple answer requires clarification. For
example, it seems that rules prohibiting murder and rape do not need
to be justifiable to, or acceptable to everyone, including those
persons who sincerely wish to engage in these actions and would prefer
that such actions be permissible. Similarly, those who hold racist and
sexist views may not find certain rules prohibiting discrimination
justified or acceptable, but that does not seem to bear on the
normative status of those rules. For this reason, among others,
virtually all proponents of public reason favor an idealized
account of the constituency of public reason. Members of the
constituency can be epistemically idealized, normatively idealized, or
both.

On Rawls’s influential account, reasonable persons
represent the constituency of public reason. Reasonable persons are
defined by their acceptance of two main ideas. First, reasonable
persons are, when among equals, “ready to propose principles and
standards as fair terms of cooperation and to abide by them willingly,
given the assurance that others will likewise do so. Those norms they
view as reasonable for everyone to accept and therefore as justifiable
to them; and they are ready to discuss the fair terms that others
propose” (Rawls 1996, 49). Second, reasonable persons accept
what Rawls calls the burdens of judgment and “accept their
consequences for the use of public reason in directing the legitimate
exercise of political power in a constitutional regime” (Rawls
1996, 54). The burdens of judgment are the many “hazards
involved in the correct (and conscientious) exercise of our powers of
reason and judgment in the ordinary course of political life,”
(Rawls 1996, 55–56) which explain how reasonable and rational
people will permanently disagree about many matters of value and
ethics. Rawls’s list of the burdens includes the following
facts: (a) empirical and scientific evidence is often complex and
conflicting; (b) we may reasonably disagree about the relative weight
of different considerations; (c) concepts are vague and subject to
hard cases; (d) the way we assess evidence and weigh values can be
shaped by our total life experience; (e) different normative
considerations on different sides can make overall assessment
difficult; and (f) the number of values any social institution can
incorporate is limited (Rawls 1996, 56–57). The burdens of
judgment explain why reasonable and rational people will be
permanently divided over matters of philosophy, religion, and other
aspects of the good life. Because reasonable persons accept these two
ideas, Rawls suggests they will also accept the idea of public
reason—the only terms of social cooperation that will seem fair
given the burdens of judgment will be terms that can be justified by
appeal to ideals or arguments that all reasonable persons can accept.
Reasonable persons will thus eschew appeals to religious ideas or
other controversial claims over which reasonable persons are assumed
to disagree, and instead appeal only to those public or political
ideas that are part of a liberal democratic political culture and can
be assumed acceptable to all persons as reasonable and rational (Rawls
1996, 217).

This Rawlsian account of the constituency of public reason is both
epistemically and normatively idealized. We can assume the
constituency of public reason includes only those persons who are
rational and so objections to proposed rules or principles cannot fail
the test of public reason simply because some people have irrational
views or have made clearly faulty inferences. But this epistemic
idealization is tempered by the fact that reasonable persons accept
the burdens of judgment; controversial claims about religion,
morality, or philosophy cannot be part of public reason. And there is
also normative idealization: the constituency includes only those who
accept certain political values or ideals (e.g. the idea of citizens
as free and equal, or society as a fair system of social cooperation).
Both idealizations have been the subject of much scrutiny and
criticism. Some suggest, for example, that there is no need for
reasonable persons to accept the burdens of judgment (Lecce 2008,
162–182; McKinnon 2002, 45–56; Wenar 1995, 41–48).
Others have argued that Rawls’s conception of the reasonable
person includes too much normative content (Bohman 2003; Habermas
1995, 126–129). Some further objections will be discussed in
section 7 below.

A somewhat less idealized view of the constituency of public reason is
offered by Gaus (2011), who suggests that we should conceptualize the
members of this constituency—he calls them Members of the
Public—as moderately idealized counterparts of the real people
to whom our moral and political rules apply. These Members of the
Public “are not so idealized that their reasoning is
inaccessible to their real-world counterparts” (Gaus 2011, 276),
but instead are idealized in the following sense: they hold the
beliefs that their real-world counterparts would be justified in
holding after engaging in a “respectable amount” of good
reasoning (Gaus 2011, 250)—reasoning that starts from the
evaluative commitments of the real-world agents they represent and
from the level of Kohlbergian moral reasoning those agents are capable
of (Gaus 2011, 277). This modest level of idealization ensures that
the constituency of public reason will be far more diverse than the
one envisaged by Rawls. This constituency will include members who
adhere to different standards of rationality and have widely divergent
sets of normative beliefs, including very divergent beliefs about
basic matters of justice. This conception of the constituency of
public reason thus purchases inclusivity, and greater approximation to
real people’s moral judgments. But this may come with a
substantial cost, since it is less clear how such a diverse
constituency may agree on any rules at all, let alone rules that we
can be confident would reflect our considered judgments about morality
and justice (Quong 2014).

On yet a different view, the constituency of public reason should be
even more inclusive with very few, if any, standards that need to be
met before one qualifies as someone to whom rules or principles must
be justified. For example, some suggest that everyone affected by some
proposed norm should be a participant in the public use of reason
regarding the validity of that norm, provided they are willing to
engage in a respectful justificatory dialogue with others (e.g. Bohman
2003). Support for this more inclusive conception can be provided by
Habermas’s account of discourse ethics (see sect. 1.1 above),
since on this account norms can only be valid when they can be the
appropriate object of a suitable intersubjective agreement amongst all
affected parties. The same worries about indeterminacy and normative
content that apply to Gaus’s moderately idealized Members of the
Public would appear apply with even greater force to this view.

The debate over the constituency of public reason has direct
implications regarding public reason’s content. The greater the
degree to which the constituency of public reason is idealized, the
more we are restricting the content of public reason, that is, the
pool of ideas or arguments that could be reasonably endorsed by the
members of the relevant constituency. And if the content of public
reason is restricted in this way, it may be possible to determine
which rules or principles are conclusively publicly justified via
philosophical analysis, without recourse to any actual deliberations
amongst citizens. Conversely, the less idealized our account of public
reason’s constituency, the more the content of public reason
will be determined by some actual process of deliberation between
agents in the real world, or at least more realistic idealizations of
such agents.

On Rawls’s view, the content of public reason has two parts
(Rawls 1996, 224). The first part consists of the principles of a
political conception of justice. Although Rawls accepts that citizens
can and will reasonably disagree about the specific content of this
conception, he claims that this disagreement will be limited to a
“family” of liberal political conceptions, all of which
share the following features: (1) a list of basic rights, liberties,
and opportunities; (2) an assignment of special priority to these
rights, liberties, and opportunities, especially when compared with
policies aimed at the general good or perfectionist values; and (3)
measures ensuring all citizens have adequate all-purpose means to make
use of their freedoms (Rawls 1996, 223; Rawls 1999b, 581–582).
Conceptions of justice, to be political, must apply to society’s
basic social and political institutions, must be able to be presented
independently of any particular view of the good life, and must be
worked out by appeal to ideas implicit in the public political culture
of a constitutional democracy (Rawls 1999b, 584). Thus, for Rawls,
some of the paradigmatic examples of the political values of justice
and public reason would include: the idea of equal basic liberties;
the idea of equality of opportunity; and principles concerning a just
distribution of income and wealth (Rawls 1999b, 584). The second part
of public reason, at least as presented by Rawls in Political
Liberalism, are guidelines of inquiry which include principles of
reasoning and rules of evidence to determine how substantive
principles are to be applied, as well as important civic virtues such
as reasonableness and civility (Rawls 1996, 224). Together, these two
components provide both the normative content and the guidelines for
citizens when engaged in public reason with one another about
fundamental political matters.

Those who adopt a more inclusive view of the constituency of public
reason object that the normative content of public reason cannot be as
determinate as Rawls suggests (e.g. Benhabib 2002, 108–112; Gaus
2011, 36–46; Habermas 1995, 126–131). On Habermas’s
view, for example, the normative content of public reason is not
something that is determined via philosophical analysis or argument.
Rather, philosophy provides a set of ideal rules or guidelines for the
conduct of public reasoning. The ideal guidelines for public reasoning
would ensure that the discussion is inclusive, public, and free from
any internal or external coercion, that anyone may raise a point that
they believe is relevant to the topic at hand, that any participant is
allowed to challenge the rules for agenda setting, and that discussion
continues until a consensus is reached (Habermas 1996, 304–305).
But on this account, the philosopher “leaves substantial
questions that must be answered here and now to the more or less
enlightened engagement of participants, which does not mean that
philosophers may not also participate in the public debate, though in
the role of intellectuals, not of experts” (Habermas 1995, 131).
In a similar vein, Gaus suggests that without making controversial
assumptions, or else idealizing the constituency of public reason in a
way that excludes too much of the diversity to which public reason is
meant to be the solution, the normative content of public reason is
largely indeterminate, that is, many different possible rules can be
justified as better than anarchy, but no philosophical argument or
analysis can establish a determinate set of rules as being uniquely
capable of meeting the test of public reason (Gaus 2011, 43–44).
On his account, the content of public reason is given determinate
content not by philosophical argument, nor necessarily by deliberation
amongst real citizens, but rather via a path-dependent evolutionary
process, whereby stable norms evolve and are selected by virtue of
their capacity to make cooperative life possible.

Although much of the debate regarding public reason’s content
has focused on the question of normative content, there are also
important questions about the other aspect of public reason’s
content—what Rawls describes as the guidelines of inquiry. Rawls
suggests that these guidelines of inquiry direct citizens to abstain
from appealing to “comprehensive religious or philosophical
doctrines—to what we as individuals or members of associations
see as the whole truth—nor to elaborate economic theories of
general equilibrium, say, if these are in dispute”. Instead he
suggests citizens must rely on “plain truths now widely
accepted, or available, to citizens generally,” which include
the conclusions of science when not controversial (Rawls 1996,
224–225). There is at least one puzzling aspect of this
proposal. As Rawls concedes, one of the things that reasonable people
disagree about is the nature of truth itself. There are competing
philosophical theories of truth, and public reason is meant to abstain
from appealing to particular philosophical doctrines. Rawls thus
famously suggests that his account of political liberalism, of which
the idea of public reason is a central part, “does without the
concept of truth” (Rawls 1996, 94). But without a concept of
truth, how can we make sense of what Rawls says about the guidelines
of inquiry, in particular his claim that citizens should rely on
“plain truths now widely accepted”? Some argue that Rawls
is mistaken, and political philosophy cannot abstain from at least
some controversial claims about the nature of truth (Estlund 1998; Raz
1990). Others accept that political philosophy must abstain from
controversial philosophical theories of truth, but insist that public
reason requires a “political” (as opposed to
philosophical) account of the truth (Cohen 2008). This is discussed
further in section 7.

In order for some proposed principle or rule, X, to meet the
test of public reason, do the reasons or arguments that justify
X need to be shared by all members of the constituency of
justification, or can X meet the test of public reason by
being justified to different people by appeal to different arguments?
This is a question about the structure of public reason, in
particular, about whether that structure must involve a kind of
consensus, or whether it can allow different people to converge on the
same rule or principle for entirely different reasons
(D’Agostino 1996, 30–31; Nagel 1987, 218–219).

One possible view would require strong consensus in order for
X to meet the test of public reason. On this account, each
member of the constituency of public reason would have to be justified
in accepting X for the very same reason or set of reasons. If
members of the constituency do not share the same justification for
X, then X would not pass the test of public reason.
Habermas might be endorsing the strong consensus view when he says
“the consensus brought about through argument must rest on
identical reasons able to convince the parties in the same
way” (Habermas 1996, 339).

A second view requires only weak consensus. On this view, it
is not necessary that each person shares the very same justification
for accepting X, but it is necessary that each person’s
justification for accepting X should depend only on
shared or public reasons, that is, reasons that all other
members of the justificatory constituency could accept as valid
considerations that provide a plausible basis for accepting
X, even if there is disagreement among the members as to
which set of shared reasons in fact provides the appropriate
justification for endorsing X. To illustrate, Albert might
believe X is justified because it follows from a commitment
to equality of opportunity, whereas Betty might believe X is
justified because it is a necessary means of protecting
individuals’ rights to freedom of religion, but so long as both
these considerations—equality of opportunity and the right to
freedom of religion—are accepted as valid normative
considerations by all members of the constituency and provide a
plausible or reasonable basis of support for X, then
X can meet the test of public reason despite the fact that
different members believe X to be justified for different
reasons. The weak consensus view of public reason’s structure
seems to reflect Rawls’s position, and has been explicitly
defended by others (Macedo 2010 (Other Internet Resources); Quong
2011, 261–273).

It may be helpful to connect this view regarding the structure of
public reason to Rawls’s discussion of the related concepts of
public justification and the idea of an overlapping
consensus. For Rawls, public justification is achieved
“when all the reasonable members of political society carry out
a justification of the shared political conception by embedding it in
their several reasonable comprehensive views” (Rawls 1996, 387).
When each reasonable person has found a sufficient comprehensive or
non-shared justification of a political liberal conception of justice,
then we can say that an overlapping consensus on a political
conception of justice exists, and as a result of this consensus, there
is a public justification of our shared political conception of
justice. But Rawls is clear that “while the public justification
of the political conception…depends on reasonable comprehensive
doctrines, it does so only in an indirect way. That is, the express
contents of the doctrines have no normative role in public
justification; citizens do not look into the content of others’
doctrines…Rather, they take into account and give some weight
only to the fact—to the existence—of the reasonable
overlapping consensus itself” (Rawls 1996, 387). For Rawls,
public justification thus depends on the fact that all reasonable
persons can endorse a political conception of justice from within
their non-public or comprehensive doctrines, but public reason itself
makes no reference to the content of those nonpublic
doctrines—it depends only on the shared political ideas found
within the political conception of justice.

By contrast, convergence accounts of public reason’s
structure allow for the possibility that a principle or rule may meet
the test of public reason even in the absence of any shared or public
reasons (Billingham 2016; Billingham 2017; Gaus 2009; Gaus 2011,
276–292; Gaus and Vallier 2009, Stout 2004, 72–73; Vallier
2014; Vallier 2016). Here is an illustration of the convergence view.
X is justified for Albert by appeal to reason Ra, but this
reason is drawn from Albert’s religious doctrine. Ra is, we can
temporarily assume, only normative for Albert and others who adhere to
this religious doctrine. For Betty, on the other hand, X can
be justified by appeal to Rb, a reason drawn from her different
religious doctrine. Suppose Albert and Betty are the only members of
the justificatory constituency and suppose there are no shared reasons
that would justify accepting X. Under these conditions, the
convergence account holds that X meets the test of public
reason because Albert and Betty each have a sufficient justification
for X, even though the reasons supporting their convergent
justifications are not shared. Note that proponents of the convergence
view need not (and typically do not) deny that shared justifications
of the sort described in the preceding paragraphs are also a
successful way for a proposed rule to meet the test of public
reason—they simply insist, contra proponents of consensus views,
that convergent justifications are also an acceptable structure for
public reason.

The convergence view appears to depend on the assumption that
justifications and reasons can be relative to particular persons, that
is, what constitutes a justification for Albert may not succeed as a
justification for Betty, and vice versa. But some have argued that
this means the convergence view depends on a controversial
philosophical position that is the subject of reasonable disagreement.
Unless this controversial view is assumed, the convergence view cannot
assure us that Albert and Betty can each sincerely believe that the
other is justified in accepting X. The convergence view,
according to this critique, thus either depends on a reasonably
disputed philosophical thesis, or else it fails to show that all
parties to a convergent justification are indeed justified in
endorsing the rule in question (Quong 2011, 261–273). Other
critics of the convergence view argue that it has unwelcome
institutional implications regarding the interpretation and
application of laws, and that unlike consensus approaches, it fails to
provide citizens with the type of mutual assurance that others are
committed to the project of public reasoning about fundamental
political matters (Macedo 2010, Other Internet Resources). Others
argue that the convergence account faces a dilemma: it either runs the
risk of self-defeat, or else it involves a form of moral
authoritarianism to which it purports to be opposed (Wall 2013).

For their part, proponents of the convergence view argue that what
matters for public reason is that rules or laws be justified to each
individual person to whom the rules or laws apply. If, as proponents
of the convergence model insist, different people can be justified in
endorsing the same rule for entirely different reasons, then
proponents of public reason have no principled basis to oppose
convergent forms of justification. Defenders of the view also insist
that the requirement for consensus or shared reasons is overly
demanding, and fails to be consistent with the pluralistic forms of
reasoning that are possible amongst the relevant members of the
constituency of public reason. Part of the point of public reason, on
this view, is to accommodate the diverse forms of reasoning that are
bound to exist among any reasonably competent group of reasoners (Gaus
2011, 288–292; Vallier, 2014; Vallier, 2016).

What duties, if any, does the idea of public reason impose on
individuals? And in what domains or parts of our life do the
requirements of public reason apply?

Rawls argues that public reason imposes a moral duty of
civility on all citizens to explain to one another how, at least
with regard to constitutional essentials and matters of basic justice,
the political positions “they advocate and vote for can be
supported by the political values of public reason” (Rawls 1996,
217). Citizens, Rawls suggests, should think of themselves as if they
were legislators, supporting only those political positions that they
believe could be justified by appeal to reasons that all reasonable
persons could endorse, and holding government officials to this
standard (Rawls 1999b, 576–577). But Rawls appears to believe
that public reason imposes greater duties on public officials: elected
officials and those who run for office, their staff, and judges. This
is because, in these roles, these people work at what Rawls considers
the main site of public reason, namely, the public
political forum. This forum has three parts: (1) the discourse of
judges, (2) the discourse of government officials, and (3) the
discourse of candidates for public office and their campaign managers
(Rawls 1999b, 575). The public political forum is the arena where our
fundamental political principles and institutions are shaped and
debated—it is where collective political power is most directly
exercised—and thus it is the most appropriate site for the
application of individual duties of public reason. When engaged in
discourse in this arena, officials are to refrain from appealing to
religious or other comprehensive doctrines over which reasonable
persons are assumed to disagree, and instead make arguments that
appeal to our shared political values. Rawls does, however, qualify
this duty by appeal to what he refers to as the “wide
view” of public political culture, which permits officials and
citizens to introduce their religious or otherwise comprehensive views
into political discussion at any point, provided appropriate public
reasons are provided in due course (Rawls 1999b, 591). It is also
important to note that the duty of civility is, on Rawls’s view,
a moral but not a legal duty—it cannot be coercively
imposed—and it does not apply to the discussions citizens may
have outside the public political forum, for example, the discussions
individuals have qua members of private associations, or family
members, or discussions within universities, religious institutions,
or other parts of what Rawls calls the background culture (Rawls 1996,
220).

Rawls’s account of the duty of civility and the site of public
reason has been subject to a number of criticisms, some of which will
be discussed in section 7 below. But even setting these objections
aside, not all proponents of public reason believe that it ought to
directly regulate the behavior of individual citizens in the manner
suggested by Rawls. Some argue that the aims of public reason are best
served by permitting ordinary citizens, and perhaps even elected
officials, to debate and deliberate unconstrained by the duty of
civility (e.g. Benhabib 2002, 108–112; Bohman 2003; Gaus 2009;
Gaus and Vallier 2009; Vallier 2014; Vallier 2016). Some argue for
this less restrictive view because they hold different conceptions of
the constituency and content of public reason; the more
philosophically indeterminate those conceptions are, the less
plausible it is to impose a restrictive duty of civility on individual
citizens, since only by allowing citizens to engage in a fairly
unconstrained discourse can the content of public reason emerge
(Benhabib 2002; Bohman 2003). Others reject the duty of civility
because they endorse a different account of the structure of public
reason. If, for example, the convergence view of public reason’s
structure is correct, then citizens and officials need not refrain
from appealing to religious or otherwise comprehensive arguments in
political deliberations, since those reasons might succeed in
justifying a proposed law to some members of the public, even if
others cannot reasonably accept those reasons. Those who endorse
consensus conceptions of public reason’s structure, however, are
likely to protest that abandoning the duty of civility in this way is
to effectively abandon the idea of public reason, since there would no
longer be any requirement that public policies be justified by appeal
to shared or common reasons.

Different accounts of public reason thus yield sharply different views
regarding the duties of citizens and public officials. On
Rawls’s view, and other similar views, citizens and public
officials should generally refrain from relying on ideas or reasons
that other reasonable citizens reject, and must always show how the
political positions they support can be justified by appeal to shared
political values. On other accounts, the idea public reason may
regulate the way we design our democratic institutions, and may be a
standard by which particular principles and laws can be assessed, but
it imposes few, if any, moral restrictions on the behavior of citizens
and perhaps even elected officials.

This section considers some of the most prominent objections to the
idea of public reason. The list below is not exhaustive, and some of
the objections below apply to some conceptions of public reason, but
not others.

As we have seen above, all conceptions of public reason involve a
certain amount of idealization. The persons to whom rules must be
justified are not persons as they actually are, with all their
prejudices, biases, and irrational beliefs. Instead, the constituency
of public reason is typically idealized on both moral and epistemic
dimensions. Critics of public reason sometimes object to this
idealization (Enoch 2013; Enoch 2015; Raz 1990). The objection is best
presented in the form of a dilemma. On the one hand, if the degree of
idealization is kept to a minimum, then public reason may result in
anarchy, or may fail to deliver minimally acceptable results; for
example, rules prohibiting discrimination on the basis of race or sex
may not be justifiable to only modestly idealized parties. On the
other hand, if the degree of idealization is very substantial, this
creates two different worries. First, it’s no longer clear in
what sense the resulting rules are justifiable to the real persons
bound by the rules. The whole apparatus of public justification might
seem superfluous (Van Schoelandt 2015); it would be simpler and more
accurate to simply present certain principles or reasons as true, and
declare that anyone who refuses to acknowledge their truth is making
an error. Second, and relatedly, too much idealization may implausibly
entail that almost all real persons are excluded from the constituency
of public reason (Enoch 2015, 122–23). The dilemma is nicely
summarized by Raz:

It seems tempting to say that our duty to act only on political
principles to which the reasonable consent is simply the duty to act
on well-founded, valid principles. For that is what the reasonable
consent to. This eliminates the independent role of consent . . . The
puzzle is how one can give consent a viable role, without saying that
only principles already agreed to by all can be relied on. One must
find a reasonable interpretation of the intuitively appealing idea
that political principles must be accessible to people as they are . .
. Politics must take people as they come and be accessible to them,
capable of commanding their consent without expecting them to change
in any radical way. But at the same time, justified political
principles may be controversial, and may fail to command actual
consent. Nagel and Rawls offer interpretations of this intuition which
aim to be both coherent and attractive. Their failure suggests that
the underlying idea may at bottom be unstable and incoherent. There
may be no middle way between actual (including implied) agreement and
rational justification. (Raz 1990, 46).

In response, several strategies are available to the proponent of
public reason. First, the proponent might aim for a Goldilocks
solutions; locate a degree of idealization that is substantial enough
to avoid the first horn of the dilemma, without being so substantial
as to generate the problems associated with the second horn (Vallier
2014, 145–180). Second, proponents of public reason might
embrace either horn of the dilemma. On the one hand, they might argue
that accounts of public reason cannot be judged by independent moral
standards. We have to follow the process of public justification
wherever it goes, even if this entails only a minimal set of rules are
publicly justifiable. On the other hand, proponents of public reason
might embrace the consequences of a great deal of idealization. In
particular, if we bear in mind that the category of the
“unreasonable” (those excluded from the constituency of
public reason) is a technical term with no necessary implications
regarding moral and political rights, there may be nothing so
counterintuitive about declaring many persons to be unreasonable.
Finally, proponents of public reason might resist the assumption, on
which the dilemma appears to rest, that one of public reason’s
central aims is to mimic the normative role that actual consent can
play in legitimating authority. If public reason is not intended to be
some pale form of consent, then it’s no longer an objection to
point out that substantial idealization might yield conclusions that
depart dramatically from what many real persons would accept.

The idea of public reason tells us that, for some set of moral or
political rules, the rules in question are not legitimate, or lack
normative authority, unless the rules in question can be justified, or
are reasonably acceptable, to all those to whom the rules apply. Some
critics argue that the idea of public reason is self-defeating because
the idea itself cannot be justified to all those to whom the idea
applies (Enoch 2013, 170–73; Mang 2017; Raz 1998, 29–30;
Wall 2002). Public reason, the critic points out, is a moral or
political rule like any other, and so surely it ought to be subject to
the same test of moral and political rules which proponents of public
reason advocate. But, the critic continues, the idea of public reason
will be unable to pass this test.

There are, broadly, two ways one might defend the idea of public
reason from this objection. First, one might deny that the idea of
public reason does indeed apply to itself. On some formulations, the
idea of public reason is a constraint on the exercise of political
power, or a constraint on the exercise of coercion, but not itself an
exercise of political power, nor an exercise of coercion. When the
proponent of public reason states that political or moral rules must
be publicly justifiably to be legitimate, she does not exert power or
coercion over anyone, she merely states a condition that any
purportedly legitimate exercises of power or coercion must meet to be
legitimate (Bajaj 2017). The success of this reply, however, may
depend on a controversial presumption in favor of states of affairs
where political power or coercion is not exercised. It seems to
assume, for example, that refusals to aid others, and other
non-coercive choices, need not meet the test of public reason.
Proponents of public reason might also argue that the principle of
public reason does not apply to itself because it is a
“meta” claim about the appropriate conditions for moral or
political justification, and not a first order normative claim within
that discourse (Gaus 2011, 227–228). But this line of reply is
also open to challenge, since the idea of public reason does sometimes
appear to operate as a first order normative claim, for example, it
can be deployed to justify why one person cannot permissibly coerce
another, or why the latter person is justified in forcefully resisting
that coercion.

The second way to defend public reason from the objection is to
concede that the idea ought to apply to itself (Estlund 1998) and
argue that it does so successfully. This strategy might be pursued in
several ways. The proponent of public reason may point to some
allegedly public or shared ideal—moral autonomy or respect for
persons—and argue that this ideal both justifies a commitment to
public reason and is publicly justifiable by virtue of being a
suitably public or shared ideal. This strategy, however, faces two
related challenges. If the ideal in question is formulated in a
sufficiently detailed or rich way, such that a commitment to public
reason is plausibly entailed by the ideal, then the ideal runs the
risk of being one that is no longer suitably public or shared. This
defense thus runs the risk of grounding public reason in some
reasonably contested moral ideal or claim about philosophical truth,
though some argue this is the only appropriate way to defend the idea
(Estlund 1998). On the other hand, if the alleged ideal is pitched at
a level of abstraction that ensures it does remain suitably public, it
may no longer be obvious that the ideal does in fact entail a
commitment to public reason (Wall 2002, 390–391). Alternatively,
a proponent might argue that public reason can successfully meet its
own test by appeal to a convergence form of justification. On this
view, the idea of public reason is justifiable or acceptable to all
the relevant members of the constituency because each member has his
or her own nonpublic reasons to accept the idea. For example, all
reasonable people might converge on the importance of the value of
justice for nonpublic reasons, and then the advocate of public reason
need only establish that justice, at least under conditions of
reasonable pluralism, requires a commitment to public reason (see
sect. 1.5 above). But this line of response may be vulnerable to the
charge that it can only succeed by stipulation—by defining the
relevant members of the constituency as those who converge on the
importance of public reason (Mang 2017).

Many accounts of public reason, most notably Rawls’s, recommend
that we assess moral and political rules while abstaining, in several
ways, from claims about truth. On Rawls’s account, for example,
philosophical theories of the truth are the sort of thing over which
reasonable people are assumed to disagree, and so an account of public
reason cannot purport to deliver moral or political principles that
are “true” according to some particular philosophical
conception of truth; rather it can only deliver principles that are
“reasonable” (Rawls 1996, 94). Many accounts of public
reason also tell citizens that they must refrain, when engaged in
public reasoning with others, from appealing to the whole
truth as they see it. Regardless of what you may believe is true
about religion or the good life, citizens must abstain from appeals to
such truths, and instead appeal only to those public or political
considerations that can be endorsed by other reasonable members of the
moral or political community.

These two ways in which public reason limits appeals to truth generate
several distinct objections. First, some worry that if a system of
moral or political justification ignores the whole truth, the
resulting moral or political principles may be false. For example, if
it is true that all sinners will go to hell when they die, but we are
precluded from appealing to this truth in developing our political
principles, we may endorse a political principle that permits people
to engage in various sinful activities. If we could appeal to the
whole truth about hell, however, we would see that this political
principle is false. Others worry that without some appeal to truth,
any agreement on political principles will amount to a mere modus
vivendi (Hampton 1989, 806–07). A related worry—that
precluding the appeal to certain truths will render us unable to solve
certain problems—is considered in section 7.3 below.

Second, we might worry that if an account of moral or political
justification seeks to validate conclusions without contradicting
anything that a diverse group of people believe to be true—for
example, without contradicting anyone’s reasonable religious
views—such an account will be “committed to the view that
it is desirable to propagate false beliefs or unsound
inferences” (Raz 1998, 42).

Third, some critics focus on Rawls’s claim that the content of
public reason—the principles of a political conception of
justice—can be presented as merely reasonable, but not true. If
these principles are merely reasonable, but not presented as true,
then why should individuals accord these principles priority in their
decisions about how to behave, particularly when these principles come
into conflict with religious or other requirements that individuals
believe to be true, and not merely reasonable (Raz 1990, 23)?

Fourth, it might seem that public reason cannot successfully abstain
from some claims about moral or political truth. In order to explain
why we ought to accept a principle of public reason or public
justification, we cannot simply say it ought to be accepted because
the principle itself can be publicly justified. Such a claim might be
trivially true—its truth established by restricting the
constituency of public reason to those who endorse the idea of public
reason—but this does not vindicate the principle, nor does it
distinguish a principle of public reason from similarly
“insular” principles that appear clearly dubious, for
example, a principle mandating that moral principles are valid only
when endorsed by Albert, who also happens to endorse this principle
granting him exclusive moral authority (Estlund 1998).

Fifth, other critics have suggested that the idea of public reason
entails that individuals must doubt, or be skeptical about, their
religious or otherwise nonpublic beliefs (Barry 1995, 901–914;
McCabe 2000, 316–324; Wall 1998, 91–94; Wenar 1995,
41–48), or at least must accept that their nonpublic beliefs can
be disputed by fully competent reasoners (Leland and van Wietmarschen
2012). Some argue this is entailed by the Rawlsian appeal to the
burdens of judgment or the fact of reasonable pluralism (see sect. 3).
Others claim that only if we were skeptical about the truth of our
nonpublic beliefs would it make sense to bracket those beliefs when
deliberating about moral and political matters. If skepticism is
entailed for either of these reasons, this poses two potential
problems. One is that this looks to be the sort of controversial
epistemological view that Rawls and others want to avoid in
constructing an account of public reason. The other is that many
otherwise apparently reasonable and well-motivated people are not
skeptical about their religious or nonpublic beliefs, but then does
this mean such people cannot endorse the idea of public reason? These
worries lead some to conclude that there is no coherent way to explain
how reasonable persons can (a) accept something like the fact of
reasonable pluralism, (b) believe her own non-public doctrine is true,
and (c) be suitably motivated to endorse a principle of public reason
(Enoch 2017).

Proponents of public reason have offered various responses to the
objections described above. First, and most generally, not all
conceptions of public reason purport to do without the concept of
truth entirely, in the way that Rawls’s particular account aims
to do. Second, even those who endorse Rawls’s account, or one
similar to it, argue that it can meet the objections pressed against
it. According to some, this is because it is a mistake to suppose that
a theory of public reason or political justification must also justify
the deliberative priority of its conclusions. On this view, it is up
to individuals to decide whether, and why, to accord to deliberative
priority to the conclusions of public reason. If deliberative priority
is not something a theory of public reason should be expected to
supply, the third, fourth, and fifth objections above can be defused
(Quong 2011, 221–242). Third, proponents of public reason point
out that when methods of justification require participants to refrain
from appealing to the whole truth, this does not entail the
conclusions reached will not be true, or that the method is somehow
indifferent with regard to the truth of the conclusions reached
(Mendus 2002, 26–28; Rawls 1996, 150). Certain appeals to
truth—for example, hearsay—are not permitted in a
courtroom, but this does not show that we are unconcerned with the
truth of the conclusions we reach in criminal trials. Fourth, and
relatedly, in contexts when we aim at truth or justification, we also
recognize the importance of other considerations and allow these
considerations to constrain the means by which truth is pursued, for
example, spouses cannot be required to testify against one another
(Freeman 2007, 233–235; Rawls 1996, 218). Finally, some might
argue, following Rawls, that we do not need to affirm any given
political principle or rule as true, only as the most reasonable one
available in light of our commitment to certain public political
values; this is sufficient to show why we ought to endorse the
principle or rule in question, at least insofar as we see ourselves as
reasonable citizens.

One of the most important objections pressed against the idea of
public reason concerns its capacity to provide solutions to all, or
almost all, of the important moral and political questions we face,
that is, the question of whether public reason is complete
(Rawls 1996, 244–246; Rawls 1999b, 585–586). A number of
critics argue that public reason lacks the resources to offer
solutions to many important moral or political questions because the
answers to these questions depend on appeal to controversial moral,
religious, or metaphysical claims of the sort over which reasonable
people disagree and that are excluded from many conceptions of public
reason, particularly those conceptions that adopt a consensus approach
to the structure of public reason (Horton 2003: de Marneffe 1994;
Reidy 2000: Sandel 1998).

There are two ways in which public reason might be incomplete (Gaus
1996, 151–158: Schwartzman 2004). First, public reason might be
indeterminate, that is, it may be unable to deliver any clear
conclusions about a particular question. In these cases, it is
sometimes said that public reason “runs out”: its content
simply proves insufficient to yield an answer to the question posed.
Second, public reason might be inconclusive with regard to
some question, that is, a plurality of different answers might be
apparently justified by appeal to public reason, and public reason
alone cannot clearly tell us which answer is correct or the most
reasonable alternative.

Indeterminacy is the more serious charge, but critics maintain that
even if public reason was only inconclusive with regard to many
questions, this would also be a serious, perhaps fatal, objection to
public reason. Some of the topics with regard to which critics allege
public reason is either inconclusive or indeterminate include:
abortion, stem-cell research, gay marriage, prostitution, justice for
future generations, the treatment of animals, and other issues where
critics allege getting the right moral or political answer depends
upon religious or metaphysical claims about personhood, or else on
controversial claims about human flourishing or the good life. Some
critics believe that virtually all moral or political questions
depend, to a certain extent, on truths about personhood, metaphysics,
or human flourishing, and so these critics are likely to see the
charge of incompleteness as a deep and pervasive problem for public
reason.

What responses are available to the proponent of public reason? With
regard to the charge of inconclusiveness, most advocates of public
reason are inclined to accept the charge, but deny that it represents
an objection (Freeman 2007, 242–243; Gaus 2011, 303–333;
Quong 2011, 204–212, 285–287; Rawls 1996, 240–241;
Schwartzman 2004; A. Williams 2000). If, for a given moral or
political question, public reason seems to yield a number of equally
reasonable answers, we should find an appropriate way to choose
between these competing answers. If we do so, the idea of public
reason is upheld, rather than undermined. On this view, the critics
wrongly suppose that the point of public reason is to deliver a unique
answer to each question we face; the point is rather to ensure that
the rules or principles that we adopt can be reasonably justified to
all. Showing that some rule we currently apply is not the only rule
that can meet the test of public reason is no objection, provided the
mechanism by which different public justifiable rules are selected can
itself be reasonably justified. The charge of indeterminacy seems more
serious: if public reason can provide no answer to a given moral or
political question, we are apparently left with no alternative but to
rely on nonpublic forms of reasoning. In response to this objection,
there are two main strategies. One is to insist that public reason is
unlikely to be indeterminate in many cases, or at least to rebut
specific attempts by critics to show that public reason is
indeterminate with regard to a particular question (Bell 2002; Freeman
2007, 241–251; Schwartzman 2004, 205–208; A. Williams
2000, 205–208). The second strategy is to insist that, even if
public reason is indeterminate with regard to a given question, this
does not suffice to establish that it is permissible to resort to
nonpublic forms of reasoning. Alternative solutions—deferring
decisions if possible, finding forms of mutual accommodation, or
random decision-making procedures—may be preferable to resorting
to nonpublic reasoning (Schwartzman 2004, 209–214; A. Williams
2000, 209–211).

Some critics argue that the idea of public reason—again
particularly Rawls’s conception—is in some way unfair or
unduly exclusionary. This complaint is most often made on behalf of
those who would rely on religious arguments when deliberating about
important moral and political questions (Eberle 2002; Greenawalt 1995;
Smith 2010; Stout 2004; Vallier 2014; Weithman 2002), though the
objection is also sometimes made more generally on behalf of those who
are excluded from the constituency of public reason on normative
grounds (Bohman 2003; Friedman 2000). There are many different
versions of this objection, and the list that follows is not
exhaustive. Put most forcefully, public reason is a sham: it purports
to be an impartial or neutral method of moral or political
justification, but it is, in fact, a form of sectarian secularism or
modern liberalism masquerading as something more inclusive. A second,
less strident, version of this objection points out that even those
theories of public reason that are not explicitly secular will
nevertheless make it more difficult, on balance, for religious
citizens to justify their favored views. Public reason cannot help but
tilt in a secular direction given its requirement that principles or
rules be reasonably justifiable to all members of the community.
Everyone can understand and endorse a variety of secular
considerations, but there is no religious idea or argument that all
reasonable people can accept, and thus public reason has an in-built
bias against religious doctrines and those who believe such doctrines
are relevant to moral and political argument. A third version of the
objection queries why controversial religious arguments, claims about
the good life, or metaphysical arguments, are excluded from playing a
role in public reason, but controversial arguments about justice or
individual rights are not similarly excluded. If, as the critic
alleges, nothing can justify this asymmetric treatment of
controversial arguments from different domains of inquiry, then the
idea of public reason is unjustifiably biased against those who rely
on religious, metaphysical, or perfectionist arguments. This objection
is sometimes called the asymmetry objection (Brower 1994,
21–22; Caney 1995, 258; Sandel 1998, 202–210; Waldron
1999, ch. 7). A variant of this objection focuses on the claim that
reasons must be “accessible” in order to qualify as
public. The critics allege that, however the notion of accessibility
is defined, there will be no clear grounds for declaring that many
religious arguments are not accessible and thus nonpublic when
compared to various apparently public non-religious arguments (Eberle
2002, 255-260). Fourth, some critics worry that Rawls’s moral
duty of civility (see sect. 6 above) will either discourage some
citizens from engaging in legitimate acts of religious expression and
association, or at least will create a political atmosphere where
religious arguments and those who espouse them are treated as less
valuable when compared with purely “public” reasons and
those who restrict themselves to such arguments (Vallier 2014,
59–64). Finally, some critics argue that public reason is not
the only way, and perhaps not the best way, to show respect for
others, or show civility, when engaged in moral and political
dialogue. There are equally plausible conceptions of respect and
civility which favor presenting others with the whole truth as we see
it when engaged in moral or political debate, rather than restricting
ourselves to shared or common reasons. If this is true, then those who
ground their moral or political arguments only in religious or
otherwise nonpublic reasons are not being unreasonable or
disrespectful: they are simply following a different, but equally
plausible, interpretation of what respect or civility requires (Eberle
2002; Stout 2004, 67–85; Weithman 2002).

A variety of different replies are available for the proponent of
public reason. In response to the first charge, defenders of public
reason can point out that it is not only religious doctrines that are
deemed “nonpublic” by leading theories of public reason
such as Rawls’s. Secular doctrines such as utilitarianism or
controversial secular claims about the good life are also deemed
nonpublic. Thus it seems unfair to allege that public reason is simply
a fig leaf for a secular agenda. In response to the second objection,
theorists of public reason may concede that there is a sense in which
public reason tilts in a secular direction, but insist this is not an
arbitrary bias, but rather the justifiable result of the requirement
that certain principles or rules be justifiable to all those who are
bound by them. The charge of bias thus in fact depends on a much
deeper objection to the public reason project, and so the critic who
presses the charge of bias must be prepared to rebut the more
fundamental arguments offered in favor of public reason.

Several different responses have been offered in reply to the third
objection: the asymmetry objection. Some argue the objection can be
defused by constructing an account of public reason (or the closely
related idea of a political liberalism) without appeal to what Rawls
calls the burdens of judgment, or other apparently epistemological
premises (see sect. 1 above) (Lecce 2008, ch. 6). Others deny that
public reason should include an accessibility requirement (Vallier
2011). Finally, others argue that it is a mistake to suppose that
religious arguments are excluded from public reason because they are
controversial or the subject or reasonable disagreement amongst
citizens, since the same can be said for many non-religious arguments.
Rather, on this view, they are excluded because the disagreements or
controversies over religious and other comprehensive doctrines are
deeper or more foundational and lack the normative common ground that
characterize reasonable disagreements over matters of justice and
individual rights (Quong 2011, 192–220).

In response to the fourth charge—that an ideal of public reason
will directly or indirectly discourage religious expression, or create
the perception that those who invoke religious arguments are, in some
sense, second class citizens—the proponent of public reason can
offer at least two replies. First, not all theories of public reason
share Rawls’s view regarding the moral duty of civility. As we
saw in section 6, some accounts of public reason entail fewer, if any,
direct restrictions on the behavior of individual citizens. Second,
Rawls’s own view does not prohibit citizens from offering
religious or nonpublic arguments for their favored positions; it only
requires that individuals who do so eventually supplement these
arguments with public reasons (again see sect. 6). Finally, proponents
of public reason are likely to deny that there are plausible
alternative conceptions of civility or respect that would allow
religious and other non-shared arguments to play a more central role
in moral or political justification (Quong 2013), or else they may
deny that the grounds of public reason are in fact best explicated by
appeal to notions of civility or respect (see sect. 1).

A further objection to the idea of public reason—again
particularly Rawls’s account—is that it is antidemocratic.
On Rawls’s account, the content of public reason is partly fixed
via philosophical argument, prior to any actual democratic
deliberation amongst citizens (see sect. 5). Seyla Benhabib thus
complains that “public reason in Rawls’s theory is best
viewed not as a process of reasoning among citizens, but more
as a regulative principle, imposing certain standards upon how
individuals, institutions, and agencies ought to reason about
public matters. The standards of public reason are set by a
political conception of liberalism” (Benhabib 2002,
108). Similarly, Habermas argues that Rawls’s theory does not
take seriously enough the importance of democratic or political
autonomy, and by giving public reason determinate content in the shape
of certain liberal principles “generates a priority of liberal
rights which demotes the democratic process to an inferior
status” (Habermas 1995, 128). Although these complaints are made
about Rawls’s account, the objection obviously applies, with
greater or lesser force, to any conception of public reason that fixes
the content of public reason, to some extent, prior to any actual
democratic debate.

The response on behalf of Rawls’s account and similar views is
likely to take the following form. First, Rawls does not purport to
offer a determinate account of public reason’s content; rather
he suggests that the content of public reason is given by a family of
political conceptions of justice. His theory thus “does not try
to fix public reason once and for all in the form of one favored
political conception of justice” (Rawls 1999b, 582). Second,
insofar as the content of public reason is partly
determinate—for example, Rawls claims it must include certain
basic rights and liberties for all persons—this does not appear
particularly objectionable, nor does it seem a problematic restriction
of the democratic process, unless one believes that democratic
majorities can permissibly vote to deny the basic rights of certain
individuals (Quong 2013). Finally, since all conceptions of public
reason aim at the public justification of moral or political rules, it
is not strange to suppose that the content of public reason might be
partly determinate prior to any actual discussion and deliberation. It
is plausible to believe that certain basic rules prohibiting
non-consensual harming of innocent persons, or protecting certain
minimal rights of bodily integrity, must be justifiable to all members
of the constituency of public reason, provided we assume those members
are committed to certain minimal ideals of freedom and equality (Cohen
2010, 272–277). To assume otherwise—as those who press the
antidemocratic objection appear to do—would be to concede that
we cannot be certain, in advance of actual deliberation amongst real
persons, that our most basic moral and political commitments are
publicly justifiable. If this assumption were true, it seems more
likely to count against the very idea of public reason, as opposed to
something that counts against Rawls’s particular conception of
public reason.

This section briefly lists some further topics that have either
received relatively little attention in the literature to date, or
have only recently become the focus of sustained work. Again, the list
is not exhaustive.

The idea of public reason is often presented as a normative ideal, as
the way our moral or political rules ought, ideally, to be
justified, and also as the way individuals ought, ideally, to
engage in deliberation and discussion. Rawls, for example, stipulates
that his account of public reason “belongs to a conception of a
well-ordered constitutional democratic society” (Rawls 1999b,
573), by which he means a society where: (a) everyone accepts, and
knows that others accept, the same conception of justice (or at least
everyone accepts some member from the family of liberal conceptions);
(b) the basic structure of society is publicly known to satisfy this
conception and; (c) citizens have a normally effective sense of
justice (Rawls 1996, 35).

But what does public reason entail in non-ideal circumstances, such as
our own, where arguably none of the three conditions listed above are
met (Boettcher 2012, 174–175)? Some proponents of public reason
encourage us to observe the moral duty of civility in our political
life, but if the duty of civility has been designed for ideal
conditions, it is unclear whether or how it might apply under less
than ideal conditions (Lister 2017). For example, many accounts of
public reason include a sincerity principle that directs individuals
to only support those principles or rules they sincerely believe meet
the test of public reason (Gaus 1996, 139–140; Rawls 1996,
241–242; Schwartzman 2011. For an alternative view see Carey
2017). But does this requirement still apply in conditions where many
of those with whom we are debating do not embrace the idea of public
reason, and may behave only strategically or cynically? Similarly, if
we believe our existing political institutions are not publicly
justifiable or do not meet certain minimal requirements of justice, do
the requirements of public reason nevertheless apply to our political
deliberations and discourse, or do those requirements only apply once
reasonably just institutions have been secured (Rawls 1996,
247–252)?

As we saw in section 7.3, an important objection to the idea of public
reason is that it will prove incomplete; that it lacks the
theoretical resources necessary to provide answers to many of the
important moral or political questions we face. Although this
objection is often voiced by critics of public reason, the existing
literature provides relatively little in the way of detailed
case-by-case analysis of the plausibility of the charge (exceptions
include J. Williams 2015; J. Williams 2017, Other Internet Resources;
Greenawalt 1988). In particular, the charge of incompleteness seems
most plausible when we consider certain “problems of
extension”, that is, topics where it is unclear whether public
reason can be extended to provide reasonable answers (Rawls 1996,
244–246). Some examples of these problems include: What
principles should regulate our treatment of future generations? What
principles should regulate our treatment of animals and nature? What
principles should apply to decisions about the provision of health
care? For each of these questions, there is a plausible prima
facie case that our deliberations must be informed by
considerations that go beyond the limits of public reason and appeal
to controversial claims about the moral status of animals, or future
persons, or particular claims about what constitutes human
flourishing. But whether this is indeed the case with regard to these
issues, among others, is something that awaits more sustained
analysis.

Another issue that Rawls lists as a problem of extension is the topic
of international relations. But the topic of international relations
may not simply be a problem of extension, that is, it may not simply
be a question of whether some existing account of public reason can be
extended to provide the necessary answers to questions about
international relations or global justice. There is also the further
question as to whether the principles that regulate international or
global justice require an independent or separate conception of global
public reason. The case in favor of a distinct account of global
public reason might appeal to at least three facts. First, if the
fundamental ideas that form the basis of “domestic” public
reason draw on the shared public or political culture of a
constitutional democracy (Rawls 1999b, 584), global public reason
appears to require a different basis, since either there is no shared
political culture spanning the globe, or else that shared culture
looks very different to that of a constitutional democracy. Second, if
the relevant agents in the global or international arena are not
primarily individual persons, but are rather states or other
collective entities, then global public reason may require a very
different conception of the constituency of public reason. Third, and
relatedly, if we assume that a global society regulated by a
conception of global public reason is comprised of different states,
which are each internally regulated by their own domestic forms of
public reason, we face several questions regarding the relationship
between these domestic and global principles, for example, can these
principles come into conflict, and if so, how do we adjudicate such
conflicts? Each of these assumptions, however, is open to dispute, and
thus some might plausibly insist that there is no need for a distinct
account of global public reason.

Although the topic of global justice has been the subject of much
recent philosophical attention, comparatively little recent work has
focused on the idea of a global public reason, with some notable
exceptions (Cohen 2010, 319–372; Porter 2012; Rawls 1999b,
529–564; Smith 2011; Wenar 2008; J. Williams 2016).

Although the idea of public reason is primarily a view about the
justification of moral or political rules, it may have other important
social functions. Paul Weithman suggests that public reason also plays
an essential role—at least in Rawls’s Political
Liberalism—in establishing mutual assurance with regard to
a commitment to a public conception of justice amongst citizens who
are deeply divided about religious, moral, and philosophical matters
(Weithman 2010, 326–335). On this view, citizens need to be
assured that others are committed to justice in order to know that
acting from their own sense of justice is not something to regret.
Without this assurance, citizens might reasonably worry that acting
justly conflicts too deeply with their narrow conception of the good,
in which case society would not be stable and well-ordered in
Rawls’s senses (see also Hadfield and Macedo 2012; Macedo 2010,
Other Internet Resources).

The extent to which the idea of public reason does or can perform this
social function depends on the answers to several further questions
(Kogelman and Stich 2016; Lister 2017; Thrasher and Vallier 2015). For
example, the potential of public reason to function as a mechanism of
mutual assurance depends on how we interpret the duties that public
reason imposes on ordinary citizens. How can ordinary citizens provide
satisfactory assurance to one another that they are, in fact,
sincerely committed to a conception of public reason? Is there an
answer to this latter question that also meets the criterion of
publicity, that is one where the specific duties of public reason are
something each person can know, and where the conformity of each with
those requirements can be common knowledge (for this construal of
publicity, see Rawls 1999a, 48–49)? Some argue that while
Rawls’s conception of public reason cannot serve as an effective
assurance mechanism, convergence models of public reason can more
successfully perform this role (Kogelman and Stich 2016).

One topic that has recently received renewed attention in the
literature on public reason concerns the extent to which the idea of
public reason is compatible with a robust commitment to political
principles of gender equality and gender justice. Skeptics have long
worried that the aspiration to justify political principles to all
reasonable persons would constrain the pursuit of gender justice. Many
if not most of the largest religions in the world endorse
inegalitarian ideals regarding the roles of men and women. If the
constituency of public reason includes persons who endorse such
religious doctrines, then it might seem strongly egalitarian
principles of gender justice will not be publicly justifiable (Okin
1994; Okin 2004).

A number of scholars, however, have argued that more robust principles
of gender justice can be derived from within the framework of liberal
public reason (Baehr 2008; Hartley and Watson 2010; Lloyd 1998;
Neufeld and Van Schoelandt 2014; Schouten 2013; Schouten 2017). These
arguments are developed in different ways, but they generally converge
on the thesis that shared public political values provide a sufficient
basis to publicly justify a range of policies designed to mitigate or
eliminate gender-based inequalities.

A different topic that has only recently begun to receive sustained
attention concerns perspectival diversity. Theories of public reason
are explicitly designed to address the fact of reasonable pluralism or
disagreement, but the disagreement is often assumed to be only about
normative or ethical matters. But persons’ diverse perspectives
can also lead to disagreement regarding how to categorize or describe
the world. Different parties to a dispute might all agree, for
example, that gratuitous harm is wrong, but disagree about whether
hate speech constitutes harm, or disagree about whether certain
creatures are capable of suffering harm. Without a shared account of
the world, it might seem the project of public reason faces grave
difficulties. Even if certain moral or political rules can be publicly
justified, our understanding and application of these rules might
radically diverge given sufficient perspectival diversity regarding
what the world looks like. Gerald Gaus and Ryan Muldoon confront this
challenge for theories of public reason in recent work (Gaus 2016;
Gaus 2017; Muldoon 2016). Both suggest that perspectival diversity is
not necessarily an obstacle to be overcome, but can also deliver
important epistemic benefits. But both also suggest existing accounts
of public reason, which often emphasize the importance of persons or
citizens sharing a common perspective, are ill-suited to realizing
these benefits.

Freeman, S., 2007, Justice and the Social Contract: Essays in
Rawlsian Political Philosophy, New York: Oxford University
Press.

Friedman, M., 2000, “John Rawls and the Political Coercion
of Unreasonable People,” in The Idea of a Political
Liberalism: Essays on John Rawls, V. Davion and C. Wolf (eds.),
Oxford: Rowman and Littlefield, pp. 16–33.

Galston, W., 2002, Liberal Pluralism: The Implications of
Value Pluralism for Political Theory and Practice, Cambridge:
Cambridge University Press.

Gaus, G., 1996, Justificatory Liberalism: An Essay on
Epistemology and Political Theory, Oxford: Oxford University
Press.